二叉树的三种遍历方式

  PS： 此算法参考资料《数据结构与算法JavaScript描述》

  1 //------------------------------------------------------------------
  2 //-----------------performance binary tree---------------------
  3 //------------------------------------------------------------------
  4 function Node(data, left, right){
  5     this.data = data;
  6     this.left = left;
  7     this.right = right;
  8     this.show = show;
  9 }
 10 
 11 function show(){
 12     return this.data;
 13 }
 14 
 15 //-----------------------二叉查找树---------------------------------
 16 function BST(){
 17     this.root = null;
 18     this.insert = insert;
 19     this.inOrder = inOrder;
 20 }
 21 
 22 //------------------------insert node-------------------------------
 23 function insert(data){
 24     var node = new Node(data, null, null);
 25     if(this.root == null){
 26         this.root = node;
 27     }else{
 28         var current = this.root;
 29         var parent;
 30         while(true){
 31             parent = current;
 32             if(data < current.data){
 33                 current = current.left;
 34                 if(current == null){
 35                     parent.left = node;
 36                     break;
 37                 }
 38             }
 39             else{
 40                 current = current.right;
 41                 if(current == null){
 42                     parent.right = node;
 43                     break;
 44                 }
 45             }
 46 
 47         }
 48     }
 49 }
 50 
 51 //-------------------中序遍历(升序遍历，从小到大)-------------------
 52 function inOrder(node){
 53     if(node != null){
 54         inOrder(node.left);
 55         console.log(node.show() + ‘ ‘);
 56         inOrder(node.right);
 57     }
 58 }
 59 
 60 //------------------中序遍历测试------------------------------------
 61 var nums = new BST();
 62 nums.insert(23);
 63 nums.insert(45);
 64 nums.insert(16);
 65 nums.insert(37);
 66 nums.insert(3);
 67 nums.insert(22);
 68 nums.insert(99);
 69 console.log(‘Inorder traversal: ‘);
 70 inOrder(nums.root);
 71 
 72 
 73 
 74 //------------先序遍历(先根节点，后左节点，右节点)------------------
 75 function preOrder(node){
 76     if(node != null){
 77         console.log(node.show());
 78         preOrder(node.left);
 79         preOrder(node.right);
 80     }
 81 }
 82 
 83 //------------------先序遍历测试------------------------------------
 84 var nums = new BST();
 85 nums.insert(23);
 86 nums.insert(45);
 87 nums.insert(16);
 88 nums.insert(37);
 89 nums.insert(3);
 90 nums.insert(22);
 91 nums.insert(99);
 92 console.log(‘preOrder traversal: ‘);
 93 preOrder(nums.root);
 94 
 95 
 96 //------------后序遍历(先叶子节点，后左节点，右节点，根节点)--------
 97 function postOrder(node){
 98     if(node != null){
 99         postOrder(node.left);
100         postOrder(node.right);
101         console.log(node.show());
102     }
103 }
104 
105 //------------------后序遍历测试------------------------------------
106 var nums = new BST();
107 nums.insert(23);
108 nums.insert(45);
109 nums.insert(16);
110 nums.insert(37);
111 nums.insert(3);
112 nums.insert(22);
113 nums.insert(99);
114 console.log(‘postOrder traversal: ‘);
115 postOrder(nums.root);
116 //------------------------------------------------------------------